Conventional belt retractors usually have a belt spool mounted rotatably in a frame and a coupling disc rotatably mounted relative to the belt spool, which coupling disc, with a rotation relative to the belt spool, can bring about a locking of the rotation of the belt spool in the unwinding direction of the safety belt.
Generic belt retractors, as known for instance from the German Utility Model 201 09 534, serve to provide safety belt band to a vehicle occupant. Normally, the belt band can be withdrawn from the belt spool against the resistance of a spring element. In the blocked state, a withdrawal of belt band is not possible, a differentiation being made basically between two blocking modes. If the blocking takes place as a function of the forces acting on the belt band, then one speaks of belt band-sensitive activation of the locking; if it is determined by the acceleration forces acting on the vehicle, one speaks of vehicle-sensitive activation of the locking.
For the belt band-sensitive activation of the locking mechanism of a belt retractor, a coupling disc is arranged on the belt spool so as to be rotatable relative thereto. If the coupling disc, owing to its mass moment of inertia, remains behind the rotation of the belt spool, then through an actuating element it causes the pivoting of a locking catch which thus can be guided into locking teeth. For vehicle-sensitive activation, the coupling disc is provided on its outer periphery with teeth into which a blocking element of a vehicle-sensitive sensor can engage, in order to thus make possible the process of guiding the locking catch into the locking teeth.
In order to make possible the renewed retraction of the safety belt, it is necessary to unlock the belt retractor. Whereas the unlocking path with belt band-sensitive locking is already very small, for the unlocking of the vehicle-sensitive locking, a shortening of the unlocking path is desired. According to prior art, in the case of vehicle-sensitive locking, additional components are required for shortening the unlocking path, which lead to increased costs with regard to components and installation.
The invention provides a belt retractor by which a drastic shortening of the unlocking path becomes possible after vehicle-sensitive locking on back rotation of the belt spool.